Starvation in Daphnia: Energy reserves and reproductive allocation1

The relationship between energy reserves (biomass and triacylglycerol) and starvation time is investigated for two planktonic Cladocera, Daphnia. galeata mendotae and Daphnia magna. Triacylglycerol storage is correlated to total individual biomass independently of body size. Adult biomass increases twofold to threefold during the intermolt, with triacylglycerol accounting for 16% of the total increase. The amount of triacylglycerol transferred into each egg depends on the adult’s feeding success. Starvation time is correlated to body mass; however, triacylglycerol storage and reproductive allocation modify the relationship. Although adult biomass and percentage of lipid both increase during intermolt, animals in late intermolt starve sooner than those in early-middle intermolt because of the transfer of energy reserves to the ovaries for reproduction. Daphnia magna neonates with high maternal lipid survived twice as long as neonates with low maternal lipid but similar body mass.